Researchers are Making Cash Machine that Spews Hot Acid at Thieves

For wannabe thieves, nothing is more tantalising than an empty street and a vulnerable ATM. Soon, though, they could be facing more than just failure. Taking design tips from mother nature herself, researchers are building ATMs that fend off thieves with a spray of hot, steaming foam.

The inspiration for this dastardly defence mechanism comes from none other than the bombardier beetle, which sprays near-boiling acid at any foes who coming knocking. It keeps the ingredients for its deadly concoction (hydrogen peroxide and hydroquinone) in two separate chambers in its abdomen. That way, the chemicals don't mix until they come shooting out, at which point the resulting reaction heats up and nearly vaporises the noxious liquid. Here's our little friend in action.

Researchers at ETH Zurich University took cues from the deadly beetle and built two chemical filled honeycomb chambers. Except this time, hydrogen peroxide was paired with manganese dioxide. Since the two are only separate by a thin sheet of lacquer, any tampering will cause the chamber to break immediately, triggering a reaction that produces water vapour, oxygen, and heat. A much less expensive—not to mention less painful—variation on the bombardier's own tactics.

Even though the thief might not walk away with a half-eaten face, this is a much more effective way of rendering ATM-theft useless. The oozing foam from the reaction will be laden with dye, marking the banknotes (rendering them useless) as well as the thieves themselves. What's more, researchers say that including DNA nanoparticles will allow them to trace the cash back to the source. Thieves may be able to run, but thankfully, it's getting much harder for them to hide.

Hopefully that barrier is thick enough to withstand the occasional (and inevitable) innocent, frustrated shake. And while this all still just being tested—no plans for immediate rollout yet—we could all use a few more acid-spitting objects in our lives. [Journal of Materials Chemistry via The Atlantic]